The present invention is directed to an inspection system wherein a component is heated by means of a laser beam to produce thermal radiation which is measured by an infrared detection system to produce an output indicative of the component characteristics and more specifically to a fiber optic system for transmitting the laser beam and the infrared radiation to and from a scanning head movable along X-Y coordinates.
The general principles of the laser beam-infrared detector inspection system are disclosed in the Vanzetti et al U.S. Pat. No. 3,803,413, granted Apr. 9, 1974. This patent discloses the concept of using a positioning table upon which an electronic circuit board assembly is positioned so that its components may be tested in sequence. As each component (in this instance a solder joint) is brought into the testing position, it is subjected to a laser beam heat injection pulse during and after which its heating and cooling history, as monitored by an infrared detection system, reveals information about its quality. In this patent, the table upon which the printed circuit board is supported is moved along one coordinate while a rotatable mirror deflects a laser beam in a scanning movement along another coordinate at right angles thereto. Upon further rotation of the mirror, the infrared radiation emitted by the heated solder joint is reflected to a suitable infrared detection system.